System information

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components are electrically noisy. The ability of the Aurender team to craft its own motherboard featuring only
the capabilities required for audio reproduction and to layout the board for the best electrical performance
separates the men from the boys. Powering this motherboard is a high quality switch mode power supply. This
supply only powers the motherboard, hard drives, and front panel OLED display.
The W20 audio board is isolated from all other parts of the server by an infrastructure of thick aluminum walls
and plates. This board contains a single oven controlled crystal oscillator and high quality parts throughout. Of
note is the special USB audio port, dual wire AES/EBU ports, and word clock BNC input. The USB audio port was
design to deliver the cleanest possible signal to a USB DAC. (The Aurender W20 has no onboard digital to analog
conversion.) Thus, the USB port's location on the audio board rather than the main motherboard. The USB audio
signal is buffered, using a proprietary buffering circuit to reduce noise and jitter, prior to transmission to a USB
Audio Class 1.0 or 2.0 DAC. The USB audio port's 5V / 1.0A power output can be toggled off and on within the
Aurender iPad application. This feature is very nice when connecting to a USB DAC that doesn't require power
from a computer such as the Ayre Acoustics QB-9 DSD. There's no sense in sending an unneeded power signal
even if it's clean as a whistle. The Aurender W20 runs a custom version of Linux that supports many external USB
DACs. There is no user interface to install special device drivers for USB DACs that aren't supported by Aurender's
Linux such as those from M2Tech (some not all models) and Mytek. I've tested several USB DACs with the W20
such as the EMM Labs DAC2X, Benchmark DAC2 D, and the Berkeley Audio Design Alpha USB. XMOS based DACs
work great for the most part. As a general rule, USB devices that work with Mac OS X without the need to install
software / device drivers will work with the Aurender W20. Users with DACs that support other audio interfaces
such as AES/EBU, coaxial S/PDIF (RCA & BNC), and optical S/PDIF (TosLink) needn't worry about compatibility
with the W20. These interfaces are standards that just work between all devices. More on the AES/EBU interfaces
in a bit.
Powering this isolated, both electrically and physically, audio board are two banks of lithium iron phosphate
(LiFePO4) DC batteries. These banks alternate charging cycles to eliminate negative performance effects of low